Bleaching and washing composition and process

ABSTRACT

A SOLID BLEACHING MIXTURE OF A PEROXYGEN COMPOUND SUCH AS SODIUM PERBORATE TETRAHYDRATE, SODIUM PERBORATE MONONHYDRATE, OR SODIUM MONOPERSULFATE, AND AN ALKALINITY BOOSTER SUCH AS SODIUM CARBONATE, SODIUM SILICATE OR TRISODIUM PHOSPHATE, EFFECIVELY REMOVES STAINS FROM HOUSEHOLD LAUNDRY WHEN THE MIXTURE IS ADDED TO THE WASH WATER IN AN AMOUNT WHICH PROVIDES BETWEEN ABOUT 50 AND 150 PARTS PER MILLION AVAILABLE OXYGEN AND A PH BETWEEN ABOUT 10 AND 12. WHEN BETWEEN ABOUT 50 AND 500 PARTS PER MILLION OF A SURFACTANT, AND BETWEEN ABOUT 5 AND 25 PARTS PER MILLION OF AN ANTI-DEPOSITION AGENT SUCH AS CARBOXYMETHYL CELLULOSE OR POLYVINYL PYRROLIDONE ARE ADDED TO THE WASH WATER EITHER TOGETHER WITH THE BLEACHING MIXTURE OR SEPARATELY, THE LAUNDERING IS PARTICULARLY EFFECTIVE. A SEQUESTERING AGENT FOR SOFTENING WATER, SUCH AS SODIUM TRIPOLYPHOSPHATE MAY BE INCLUDED.

Oct. 10, 1972 BLEACHING 2O 5O AVAILABLE OXYGEN ppm INVENTOR. LODRIC L.MADDOX ATTORNEYS United States Patent 3,697,217 BLEACHING AND WASHINGCOMPOSITION AND PROCESS Lodric L. Maddox, Oakland, Calif., assignor toThe Clorox Company, Oakland, Calif. Filed Jan. 26, 1970, Ser. No. 5,600

Int. Cl. D061 3/02 US. Cl. 8---111 2 Claims ABSTRACT OF THE DISCLOSURE Asolid bleaching mixture of a peroxygen compound such as sodium perboratetetrahydrate, sodium perborate monohydrate, or sodium monopersulfate,and an alkalinity booster such as sodium carbonate, sodium silicate ortrisodium phosphate, effectively removes stains from household laundrywhen the mixture is added to the wash water in an amount which providesbetween about 50 and 150 parts per million available oxygen and a pHbetween about 10 and 12. When between about 50 and 500 parts per millionof a surfactant, and between about and 25 parts per million of ananti-deposition agent such as carboxymethyl cellulose or polyvinylpyrrolidone are added to the wash water either together with thebleaching mixture or separately, the laundering is particularlyeffective. A sequestering agent for softening water, such as sodiumtripolyphosphate may be included.

BACKGROUND OF THE INVENTION Many bleaches have been used for homelaundry purposes. Chlorine bleaches are excellent stain removers.However, the liquid hypochlorite bleaches must be packaged in bottles,and the chlorinated cyanuric acid bleaches are relatively expensive.Furthermore, chlorine bleaches must be used with care when bleachingprotein fibers, such as silk, wool and mohair.

In an attempt to provide a solid stain remover for use in the homelaundry, proteolytic enzymes have been mixed with packaged detergents.However, such enzymes are of limited effectiveness, since they areprimarily effective only against protein stains, such as blood.

Peroxygen bleaching agents are known and employed in the textilemanufacturing art for the removal or reduction of undesirable naturalcolor bodies from new fabrics, yarns and fibrous materials. The meansand conditions necessary to effect this purpose are in general severe interms of temperatures, pressures and operating methods, and they includenumerous stages and manipulations and are not practical for householduse.

The wash cycle in an automatic household laundry unit is normally run ata temperature ranging from about 80 F. to 140 F. and at a pH below about10. In the absence of suitable additives such as activators, catalysts,and the like as known in the art, perborate-containing bleaches appearto be ineffective or require impracticably long contact times for thetreatment of household laundry at such temperatures and pH values. Theincorporation, on the other hand, of activators, catalysts, and the likein a solid bleach composition is undesirable for many reasons includingcost, added process burden, and product stability on aging.

SUMMARY OF THE INVENTION It has now been found that a solid, granularbleaching mixture of a peroxygen compound selected from the groupconsisting of sodium perborate, sodium monopersulfate, and mixturesthereof, and an alkalinity booster selected from the group consisting ofsodium carbonate, sodium silicate trisodium phosphate and mixturesthereof, proice vides unusually effective bleaching under home laundryconditions when the peroxygen compound and alkalinity booster areproportioned so that the alkalinity booster provides a pH of betweenabout 10 and 12 when a solution of the bleaching mixture containsbetween about 50 and parts per million available oxygen. The addition ofbetween about 50 and 500 parts per million of a surfactant, and between5 and 25 parts per million of an anti-deposition agent, eitherintermixed with the bleaching mixture in the dry form or introducedseparately into the wash water provides particularly effective washingand bleaching. Advantageously a sequestering agent is also incorporatedfor softening the Wash water in the laundering" process.

The instant bleaching mixture is dry and granular. It may be packagedand stored in any porous paperboard container Without a vapor barrier,and yet it remains a readily pourable mixture which is convenient foruse in the home laundry.

Surprisingly the compositions hereof are effective bleaching agents forhousehold laundry uses in the relatively short, i.e. 10 to 20 minute,cleaning cycles of automatic household laundry units in the absence ofadded acylated organic nitrogenous activators such as N-benzoylsuccinimide (see US. Pat. No. 3,061,550), acyl organoamides (see US.Pat. No. 3,177,148), carboxylic acid amides (see US. Pat. No. 2,898,181)and polyarylamines (see US. Pat. No. 3,163,606); of enhancing agentssuch as sodium p-acetoxybenzene sulfonate (see US. Pat. No. 3,185,649);of transition metal cationic catalysts (see US. Pat. No. 3,398,096); orof modified organic acid anhydrides (see for example US. Pat. No.3,298,775).

By household laundry is meant clothing and fabrics made of natural andsynthetic fibers and mixtures thereof, particularly the cotton, linenand nylon and polyestertype textiles normally used in the home.

By the bleaching and/or treatment of household laundry as used herein ismeant the removal or substantial reduction of stain, i.e. foreigncoloring matter, from clothing and household textiles.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a graph whichillustrates the total change 1n color of swatches stained with ink asthe available oxygen content provided by the peroxygen compound isincreased. The graph contains four curves for four different pH values.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In greater detail the availableoxygen which provides active bleaching is obtained from a solidperoxygen compound preferably selected from the group consisting ofsodrum perborate, sodium monopersulfate and mixtures thereof. The sodiumperborate may be in the form of the tetrahydrate or the monohydrate.Sodium perborate tetrahydrate provides about 10.4 percent availableoxygen, sodium perborate monohydrate provides about 16.0 percentavailable oxygen, and sodium monopersulfa te provides about 4.5 percentof its weight available oxygen when dissolved in the wash Water.

The alkalinity booster is provided by sodium carbonate, sodium silicate,trisodium phosphate or mixtures thereof. A sufiicient amount of the dryalkalinity booster is mixed with the peroxygen compound to provide a pHof between 10 and 12 when between about 50 and 150 parts per millionavailable oxygen is provided to the wash Water by I the peroxygencompound. It is apparent that the ratio of peroxygen compound toalkalinity booster will vary greatly because of the different amounts ofavailable oxygen provided by the various peroxygen compounds, and

the difference in alkalinity of the alkalinity boosters as well as thebulfering effect of the surfactant and/or surfactant builders. However,the ratio of alkalinity booster to peroxygen compound which provides thedesired pH range for different alkalinity boosters and peroxygencompounds may readily be determined in each case by simple pHmeasurements.

A conventional sequestering agent for softening the water may be addedto the bleaching mixture of the peroxygen compound and the alkalinitymixture to enhance the washing effect. Suitable sequestering agentsinclude sodium tripolyphosphate, sodium nitrilo acetate and ethylenediamine tetracetic acid. An amount of sequestering agent proportioned toprovide between and 2000 parts per million sequestering agent for each50 to 150 parts per million available oxygen may be included in the drybleaching mixture.

In a preferred embodiment of solid free flowing bleaching composition isprepared by dry mixing particulate granules of sodium carbonate, sodiumperborate tetrahydrate and sodium tripolyphosphate. Optionally and foraesthetic reasons minor amounts in the range 0.01 to 0.2 part each, ofconventional additives may be included in the mix, such as for example:(1) ultramarine blue coloring agent (2) perfume, (3) antidust agents,and (4) optical brighteners. Inert fillers such as sodium sulfate mayalso be added.

The solid compositions of the instant invention may be formulated asWell-blended, 'i.e. essentially homogeneous, granular mixes or may betableted in a variety of sizes and shapes as desired. Whatever the form,the solid mix rapidly dissolves in water.

A particular advantage of the solid bleaching composites of the presentinvention is that they can be effectively applied for stain removal fromhousehold laundry during the washing cycle. Detergents or surfactants ingeneral as known in the art are satisfactory for use in conjunction withthe instant composites. In a corollary aspect herein these surfactantscan be added as a fourth major component to the present drybleach-containing mixtures. Either anionic or nonionc detergents areused in an amount sufiicient to provide between about 50 and 500 partsper million surfactant in the wash Water when the amount of peroxygencompound is between about 50 and 150 parts per million. Representativesurfactants which may be used in this manner include alkylbenzenesulfonates and sulfated alcohol-ethoxylates, and such nonionics as alkylethoxylates.

An anti-deposition agent is added to the wash water along with thesurfactant. The anti-deposition agent may be added separately or in asolid mixture with the peroxygen bleaching composition. Suitableanti-deposition agents include polyvinyl pyrrolidone, carboxymethylcellulose and polyvinyl alcohol. Between about 5 and 25 parts permillion anti-deposition agent is used in the wash water.

Extremely effective bleaching and washing is provided by the followinghome laundry wash water composition:

Alkalinity booster: pH to 12 Peroxygen compound: 50 to 150 p.p.m.Sequestering agent: 0 to 2000 p.p.m. Surfactant: 50 to 500 p.p.m.Anti-deposition agent: 5 to 25 p.p.m.

The pH provided by the alkalinity booster is an important factor. Belowa pH of 10, the oxygen is released too slowly from the peroxygencompound and the bleaching is not very effective. Above a pH of 12,damage to hands and clothes may occur.

Also, bleaching is not very effective when the amount of availableoxygen provided by the peroxygen compound is less than 50 parts permillion. Above about 150 parts per million, the extra oxygen is oflittle additional value.

The sequestering agent is not essential, depending upon the nature ofthe water. However, it is of great value in enhancing washing in hardwater areas.

When the amount of surfactant is less than about 50 Na co, 53.55 NaBO.4H O 30.00 Na P O Small amounts of ultramarine blue coloring agent,perfume antidust agents and commercial optical brighteners totaling 0.45part by weight were also added to the solid mixture to bring the totalto parts by weight.

One-half cup (about grams) of the solid bleaching mixture was added to ahousehold washing machine containing 17 gallons or about 64,000 ml.water. This provided about 36 grams of sodium perborate to the washwater resulting in about 3.6 m p.p.m.

available oxygen, and a pH of about 10.2 measured after addition of thedetergent. The detergent mixture added to the wash water provided thefollowing additional ingredients to the water:

P.p.m. Alkylbenzene sulfonate 320 Sodium tripolyphosphate 800 Sodiummetasilicate 95 Sodium sulfate 375 Carboxymethyl cellulose 10 Clothesstained with ink, blood and mustard were placed in the wash water. Theclothes were washed for 10 minutes at a water temperature of about 120F., and dried in a tumbler drier for about 20 to 25 minutes. The stainremoval was excellent.

Also, tests were conducted at varying available oxygen contents and atdifferent pH levels and the bleaching effectiveness of the bleachingmixtures hereof was measured quantitatively. Representative stains werepadded onto commercially available unbleached cotton muslin test cloth.The stained cloth was cut into swatches, each swatch was numbered andHunter D25 Color Difference meter readings were made on the testfabrics. There were then attached to carrier towels and the assembly waswashed, dried, pressed wrinkle-free and reread on the color meter. Thetotal change in the color values between unwashed and washed testswatches indicated the amount of stain removed during the test asfollows:

E=Total change in color L=Mean change in lightness value a=Mean changein green/red value b=Mean change in blue/yellow value The waterwashing-bleaching operation was carried out in a commercial automaticlaundry unit having a normal cleaning cycle of 10 minutes and employinga cleaning solution volume of 16.5 gallons (120 p.p.m. water hardness)at 120:3" F. One hundred grams of a representative detergent, a linearalkylbenzene sulfonate composite:

Parts (wt.)

Linear alkylbenzene sulfonate d 20 Sodium tripolyphosphate 50 Sodiummetasilicate 6 Sodium sulfate 23.5 Sodium carboxymethyl cellulose 0.5

plus the carrier towels and ballast towels sufficient to provide adive-pound load, were charged to the washer followed by a solid granularmixture of sodium perborate tetrahydrate, sodium carbonate and sodiumtripolyphosphate proportioned to provide the pH and available oxygenvalues set forth in Table 1 below. Drying, ironing and reading understandardized conditions completed the test.

Permanent blue-black ink is a representative stain encountered inhousehold laundry and was, for that reason, selected for the test withthe following results which are plotted in graph form in the drawing:

TABLE I Available Stain H 01 E Stain removal Permanent blue- 9 51.1Poor.

black ink. 20 56. 1 Do. 40 525.0 D0. 60 58.0 Do. 80 54.6 Do. 100 54.6Do.

10.0 0 52.3 Poor.

20 53.7 D0. 40 56.8 Do. 60 65.5 Fair. 80 74. 9 Excellent. 100 76.5 Do.

10.5 0 50.6 Poor.

20 56.7 D0. 40 64.6 Fair 60 67.1 Good. so 76.8 Excellent. 100 76.7 Do.

11.0 0 51.4 Poor.

20 60.1 D0. 40 68.3 Fair. 60 74.5 Excellent. 80 77.7 D0. 100 76.1 Do.

The foregoing examples demonstrate that the bleach composites herein areeifective stain removal agents for use in automatic household laundry attemperatures substantially below 140 F.

What is claimed is:

1. The method of bleaching stains in household laundry which comprisesadding to wash water containing said laundry a solid, soapless, granularbleaching and stain removing mixture consisting essentially of aperoxygen compound selected from the group consisting of sodiumperborate, sodium monopersulfate, and mixtures thereof; and analkalinity booster selected from the group consisting of sodiumcarbonate, trisodium phosphate, Water soluble sodium silicate andmixtures thereof; said alkalinity booster being added in an amount toprovide a pH in the wash water of between about 10 and 12 and saidperoxygen compound being added in an amount to provide between and 150parts per million available oxygen in the wash water.

2. The method of claim 1 wherein said solid mixture also contains sodiumtripolyphosphate present in an amount up to 2000 parts per million foreach 50 to 150 parts per million of available oxygen.

References Cited UNITED STATES PATENTS 1,628,015 5/1927 Welsher 252-972,576,205 11/19'51 Apperson 25299 3,337,466 8/ 19-67 Puetzer et a1. 252-X 3,372,125 '3/1968 Hill 252-99 3,384,596 5/1968 Moyer 252-99 X FOREIGNPATENTS 871,814 7/1961 Great Britain 25299- MAYER WEINBLATI', PrimaryExaminer US. Cl. X.R. 252-85, 97, 99, 186

